igneous
Pumice
Pumice; highly vesicular volcanic rock, commonly silica-rich volcanic glass with feldspar and minor other minerals
AI-generated identification · may be incorrectLight gray-beige, dull to slightly glassy, porous and rough; typically Mohs 5–6, with no consistent cleavage. The specimen’s small size and appearance do not allow precise identification.
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Physical properties
Light gray-beige, dull to slightly glassy, porous and rough; typically Mohs 5–6, with no consistent cleavage. The specimen’s small size and appearance do not allow precise identification.
Formation & geological history
Forms when gas-rich lava rapidly cools during explosive eruptions, trapping abundant bubbles. It can occur in volcanic deposits of many ages.
Uses & applications
Used as an abrasive, lightweight aggregate, horticultural soil additive, and in polishing products; suitable pieces are also collected.
Geological facts
Pumice is so vesicular that many pieces float temporarily, though this specimen’s buoyancy cannot be determined from the image.
Field identification & locations
The pale color and many cavities are consistent with pumice; check that it is unusually lightweight and full of pores. Found near volcanic regions worldwide, including Italy, Iceland, and the western United States.
